- age toned
Age tanning, or browning, occurs over time on the pages of books. This process can show up on just the edges of pages, when this occurs it is sometimes referred to as "edge tanning." This kind of deterioration is commonly seen in books printed before the advent of acid-free paper in the 1980s. In 1984, The American National Standards Institute (ANSI) adopted a voluntary standard under the umbrella of the National Information Standards Organization (NISO), that provides consistency for the production of acid-free paper resistant to tanning and other forms of aging.
NISO was founded in 1939 as a volunteer organization, and in 1983 became a non-profit corporation accredited by ANSI. NISO's membership is composed of organizations that include libraries and archives, as well as prominent publishers and IT groups. In addition to paper standards, this group works to ensure the integrity of information in every form.
Archivists have long dealt with the problem of deteriorating books and papers. While processes developed in the 1930s and standardized in the 1980s make this issue less of a problem for newer volumes, the browning of pages in older books will continue to be both part of the charm and challenge of book collecting.